| /* |
| * Copyright (C) 2009 The Android Open Source Project |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| package android.app.backup; |
| |
| import android.content.Context; |
| import android.content.SharedPreferences; |
| import android.os.ParcelFileDescriptor; |
| import android.util.Log; |
| |
| import java.io.File; |
| |
| /** |
| * A helper class which can be used in conjunction with |
| * {@link android.app.backup.BackupAgentHelper} to manage the backup of |
| * {@link android.content.SharedPreferences}. Whenever a backup is performed it |
| * will back up all named shared preferences which have changed since the last |
| * backup operation. |
| * <p> |
| * To use this class, the application's agent class should extend |
| * {@link android.app.backup.BackupAgentHelper}. Then, in the agent's |
| * {@link BackupAgent#onCreate()} method, an instance of this class should be |
| * allocated and installed as a backup/restore handler within the BackupAgentHelper |
| * framework. An implementation of an agent supporting backup and restore for |
| * an application that wishes to back up two groups of {@link android.content.SharedPreferences} |
| * data might look something like this: |
| * <pre> |
| * import android.app.backup.BackupAgentHelper; |
| * import android.app.backup.SharedPreferencesBackupHelper; |
| * |
| * public class MyBackupAgent extends BackupAgentHelper { |
| * // The names of the SharedPreferences groups that the application maintains. These |
| * // are the same strings that are passed to {@link Context#getSharedPreferences(String, int)}. |
| * static final String PREFS_DISPLAY = "displayprefs"; |
| * static final String PREFS_SCORES = "highscores"; |
| * |
| * // An arbitrary string used within the BackupAgentHelper implementation to |
| * // identify the SharedPreferenceBackupHelper's data. |
| * static final String MY_PREFS_BACKUP_KEY = "myprefs"; |
| * |
| * // Simply allocate a helper and install it |
| * void onCreate() { |
| * SharedPreferencesBackupHelper helper = |
| * new SharedPreferencesBackupHelper(this, PREFS_DISPLAY, PREFS_SCORES); |
| * addHelper(MY_PREFS_BACKUP_KEY, helper); |
| * } |
| * }</pre> |
| * <p> |
| * No further implementation is needed; the BackupAgentHelper mechanism automatically |
| * dispatches the |
| * {@link BackupAgent#onBackup(android.os.ParcelFileDescriptor, BackupDataOutput, android.os.ParcelFileDescriptor) BackupAgent.onBackup()} |
| * and |
| * {@link BackupAgent#onRestore(BackupDataInput, int, android.os.ParcelFileDescriptor) BackupAgent.onRestore()} |
| * callbacks to the SharedPreferencesBackupHelper as appropriate. |
| */ |
| public class SharedPreferencesBackupHelper extends FileBackupHelperBase implements BackupHelper { |
| private static final String TAG = "SharedPreferencesBackupHelper"; |
| private static final boolean DEBUG = false; |
| |
| private Context mContext; |
| private String[] mPrefGroups; |
| |
| /** |
| * Construct a helper for backing up and restoring the |
| * {@link android.content.SharedPreferences} under the given names. |
| * |
| * @param context |
| * @param prefGroups |
| */ |
| public SharedPreferencesBackupHelper(Context context, String... prefGroups) { |
| super(context); |
| |
| mContext = context; |
| mPrefGroups = prefGroups; |
| } |
| |
| /** |
| * Backs up the configured SharedPreferences groups |
| */ |
| public void performBackup(ParcelFileDescriptor oldState, BackupDataOutput data, |
| ParcelFileDescriptor newState) { |
| Context context = mContext; |
| |
| // make filenames for the prefGroups |
| String[] prefGroups = mPrefGroups; |
| final int N = prefGroups.length; |
| String[] files = new String[N]; |
| for (int i=0; i<N; i++) { |
| files[i] = context.getSharedPrefsFile(prefGroups[i]).getAbsolutePath(); |
| } |
| |
| // go |
| performBackup_checked(oldState, data, newState, files, prefGroups); |
| } |
| |
| /** |
| * Restores one entity from the restore data stream to its proper shared |
| * preferences file store. |
| */ |
| public void restoreEntity(BackupDataInputStream data) { |
| Context context = mContext; |
| |
| String key = data.getKey(); |
| if (DEBUG) Log.d(TAG, "got entity '" + key + "' size=" + data.size()); |
| |
| if (isKeyInList(key, mPrefGroups)) { |
| File f = context.getSharedPrefsFile(key).getAbsoluteFile(); |
| writeFile(f, data); |
| } |
| } |
| } |
| |